Ian’s A to Z – C is for Chromatic Aberration

Ian’s A to Z – C is for Chromatic Aberration
22 Feb 15

Welcome to Ian’s A to Z of photography.  A new word each week here on BTN!  My words, and my take on them.  Nothing too technical, just stuff important to me that I hope you find useful!

Chromatic Aberration

There are many technical terms in photography and chromatic aberration (CA for short) is one of those.  Photography is all about light and in more ways than one.  When you take that shot of the green leaf you are not actually seeing a green leaf as you know it, rather a leaf that happens to reflect the green wavelength of light.  How your lens handles the light can have an impact on the final image.

Lenses are typically made up of many ‘elements’ or more simply put different planes of glass.  The ultimate goal of a lens is to ensure the light passes through the elements on to the sensor with the ultimate goal that all the different wavelengths will come together at the same time onto the sensor.  Therefore giving you a sharp and colour accurate image.  As you can imagine, with so many varying factors such as the number of elements, size of the aperture and high contrast scenes this isn’t always possible and the result can be CA.  So what is CA?

CA occurs when the wavelengths of light do not combine together on the sensor at the same time.  Take a look at the below image.  There is obvious CA or ‘colour fringing’ at the edges of the subject.  To the top of the branches there is some green fringing and below purple fringing.


chromatic aberration

The good news is that you’ll only really notice this if looking at your images at 100% in high contrast areas.  It is important to know your lenses.  Depending on their quality, you may see little or no CA.  On other lenses you will find some apertures work better than others.  But the really good news is CA can in most cases be easily fixed in post processing.



Ian Lewis


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